ISSUE-41: (Bugzilla 17398) AudioNode as input to AudioParam underdefined

AudioNodeAsAudioParam

(Bugzilla 17398) AudioNode as input to AudioParam underdefined

State:
CLOSED
Product:
Web Audio API
Raised by:
Philip J├Ągenstedt
Opened on:
2012-05-15
Description:
The output of an AudioNode can be connected with to an AudioParam value using AudioNode.connect(). Does that override scheduled value changes, or is the whole AudioParam interface "dead" in that case? In other words, which value takes priority, or are the mixed? (Similar to issue with multiple ramps.)

What happens if the input has multiple channels, which channel is used or is there implicit mixing?

Does AudioParam.unit affect how the input signal is mapped to a value?
Related Actions Items:
No related actions
Related emails:
  1. [web-audio-api] (AudioNodeAsAudioParam): AudioNode as input to AudioParam underdefined (#159) (from notifications@github.com on 2013-09-11)
  2. Re: third public Working Draft of the Web Audio API available (from tmichel@w3.org on 2012-08-02)
  3. Re: Summary of issues (from crogers@google.com on 2012-05-22)
  4. Summary of issues (from mage@opera.com on 2012-05-22)
  5. Re: Missing information in the Web Audio spec (from philipj@opera.com on 2012-05-16)
  6. Audio-ISSUE-41 (AudioNodeAsAudioParam): AudioNode as input to AudioParam underdefined [Web Audio API] (from sysbot+tracker@w3.org on 2012-05-15)

Related notes:

Still need to edit the spec to answer these, but here's the quick answer:

The output of an AudioNode can be connected with to an AudioParam value using AudioNode.connect(). Does that override scheduled value changes, or is the whole AudioParam interface "dead" in that case? In other words, which value takes priority, or are the mixed?

ANSWER: they are all mixed together (the AudioParam interface is not "dead"). I can give a good motivation for why this is important and useful...


What happens if the input has multiple channels, which channel is used or is there implicit mixing?

ANSWER: Normally the developer would connect "mono" inputs (for LFOs, AM, FM effects, noise modulation, etc.) However, in the case where an audio-source is >1 channel (stereo, 5.1, etc.) it will be mixed down to mono before being summed with the other audio sources and the "intrinsic" parameter value. The mixdown will happen according to the mixdown rules in the specification (still need to expand that one a little bit, but we're mostly there)


Does AudioParam.unit affect how the input signal is mapped to a value?

ANSWER: no, in fact ".unit" may be a good candidate to remove from the spec

Chris Rogers, 18 May 2012, 23:47:51

Editor working on a response. Setting as OPEN.

Olivier Thereaux, 30 May 2012, 20:18:17

Added detailed text:
https://dvcs.w3.org/hg/audio/rev/1fbfc8e7b350

Chris Rogers, 4 Jun 2012, 23:41:40

[MikeSmith]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=17398

5 Jun 2012, 13:09:35

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